package demo01;

class Aircondition {
    private int number = 0;

    public synchronized void increment() throws Exception {
        // 1 判断
//        if (number != 0) {              # 这里一定要用while，官方文档wait有介绍，如果用if，多个线程会出错
        while (number != 0) {
            this.wait();
        }

        // 2 干活
        number++;
        System.out.println(Thread.currentThread().getName() + "\t" + number);

        // 3 通知
        this.notifyAll();
    }

    public synchronized void decrement() throws Exception {
        // 1 判断
//        if (number == 0) {
        while (number == 0) {
            this.wait();
        }

        // 2 干活
        number--;
        System.out.println(Thread.currentThread().getName() + "\t" + number);

        // 3 通知
        this.notifyAll();
    }
}



/**
 * 题目：现在两个线程，可以操作初始值为0的一个变量
 * 实现一个线程对变量加1，一个线程对变量减1，
 * 实现交替，来10轮，变量初始值为0
 *
 * 1 高内聚低耦合前提下，线程操作资源类
 * 判断/干活/通知
 */
public class ProdConsumerDemo04 {
    public static void main(String[] args) throws Exception{
        Aircondition aircondition = new Aircondition();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    aircondition.increment();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, "A").start();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    aircondition.decrement();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, "B").start();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    aircondition.increment();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, "C").start();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    aircondition.decrement();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, "D").start();
    }
}
